Yprésien is the oldest stage of the Eocene era (Tertiaire). It extends from 55 with 49  My. It was defined by André Dumont in reference to the town of Ypres in Belgium.

Yprésien saw appearing the first Primate S and the first équidé S.

It is sometimes broken up into:

See too

• geological time scale
• Given site '' Geowhen ''